* Upset usually implies a stronger, more emotional reaction. It suggests being disturbed, troubled, or even angered.
* Disappoint suggests a feeling of sadness or dissatisfaction because something did not meet your expectations. It's a milder emotion than upset.
Example:
* You might be disappointed if a friend forgets your birthday.
* You might be upset if a friend betrays your trust.
In summary:
* Disappoint is a more general term for a negative feeling when something falls short.
* Upset implies a stronger emotional response, often involving anger or frustration.
While they can overlap in meaning, "upset" is generally a more intense word than "disappoint."